The Israeli army said the campus on a northern Gaza hilltop overlooking the Mediterranean had been used as a launching base for rockets and was a legitimate target.

Israel has been bombing Hamas targets in Gaza for the last eight days to stop the group from sending rockets into southern Israel. More than 470 Palestinians have died so far, along with four Israelis.

Most of the school's buildings, which offered American-style curriculum in English for kindergarten through 12th grade, were destroyed by the strikes, which also killed the night watchman.

"This is the most distinguished and advanced school in Gaza, if not in Gaza and the West Bank," said Iyad Saraj, chairman of the school's board of trustees. "I cannot swear there was no rocket fired, but if there was, you don't destroy a whole school ... this is the destruction of civilization."

The school was founded in 2000 to provide "progressive education," according to the school's Web site. The school has no connection to the US government.

Saraj said the school had 250 students and many of its graduates went on to US universities such as Harvard, MIT and Princeton. "They are very good, highly educated open-minded students who can really be future leaders of Palestine," he said.

The school was damaged a year ago when gunmen broke in, burned six school buses, smashed windows and computers on the eve US President George W. Bush's visit to the West Bank.

A previously unknown group, The Holy Jihad Brigades, said it was behind that attack. Vandals have repeatedly targeted the school in the past for its perceived US link.

Radical Islamists had criticized the school for its Western-style curriculum and coed classes. Most schools in the strip are single sex.

The school was built at a cost of $5 million dollars by the Palestinian Investment Fund, a government fund created in 2000 to improve the Palestinian economy in partnership with the private sector.